Since the beginning of the eighties the odontology field has gone through a strong development in the field of implants with the advent of the root implants described by Branemark et al. This development allowed dentists to regularly execute surgeries, which until then were not so frequent, aiming to fix a implant part or piece in the maxillary or jawbone of a patient.
Indeed, the use of oral implants for the restoration of total or partial edentulism became a quite accepted practice in present odontology, as it allows the replacement of lost teeth with a corresponding dental prosthesis. This technique consists of a first surgical phase when a implant part is positioned inside the maxillary or jawbone, either in the form of a raw machined surface part or with the addition of bio-compatible substances or by the subtraction of material, so as to perfectly integrate it to the receiving locus. In the case of addition one can employ, e.g., plasma spray, hydroxy apatite and other suitable materials, and, when subtracting, one can employ mechanical abrasion or acid attack techniques.
There are many known formats for the implant parts. Their basic structure, however, consists of a cylindrical wad or sleeve made of a special material, generally of noble and resistant materials, such as a titanium cylinder externally threaded in its lateral surface and with a passing axial internal channel, provided with an internal thread. During the surgical procedure, the patient maxillary or jawbone is perforated, and a implant part or cylindrical sleeve is firmly retained therein by means of the coupling of the external thread with the bone.
After the healing period determined by the dentist, dependent on the type of bone, the bone quality, etc., a second surgical procedure is effected for the positioning of a connecting element between the implant part, located inside the gum, and a crown body to be built. The term crown means the supra-gingival portion of the implant part or of a tooth.
After the second surgical procedure has healed, a mold is prepared for the manufacture of the patient buccal model, which is nothing but the faithful reproduction of the patient dental structure. During this step are taken the patient articulation registers or records; these are the records which shall determine the relative mutual position of both superior and inferior arcades.
With the models and registers it is then possible to proceed with the mounting on the articulation structure, with which begins the laboratory phase of rehabilitation.
During this laboratory phase it is determined the type of element to be used and the manufacture of the crown. The connecting element is in itself an union part between the implant part and the crown.
The presently available connecting elements exist in many forms; some are pre-fabricated, and over these one can position metallic or ceramic cylinders which will support the future crown; others consist of wax or plastic components, which are models manually sculptured by the prosthetic technician, which, after casting, can receive the future crown.
The connecting elements may consist, e.g., of a cylinder having a transfixing internal channel, coaxial with the cylinder geometric axis, said cylinder being fixedly coupled to the implant part already embedded in the maxillary or jawbone of the patient. The firm contact between the cylinder and the implant part is generally effected by means of a fastening threaded screw inserted within the cylinder internal channel, which cooperates with, or is threaded within, the internal thread of the internal threaded channel of the implant part.
The seating surface of the implant part may be provided with an anti-rotation means so as to prevent the rotary motion between the implant part and the connection element. This anti-rotation means may take the form of a hexagon, a Morse cone, or any other format. However, the presence of a anti-rotation means on the seating surface of the connection element is optional, as it is specific for each case.
When a anti-rotation means is used, it may consist, for example, of a projection or shoulder with an hexagonal form, or of a Morse cone, provided on the seating surface of the implant part, and of a corresponding recess provided in the seating surface of the connection element. When the connection element is positioned over the implant part, the projection on the implant part settles in the corresponding recess of the connection element and establishes a male-female type connection and prevents the relative rotation of these components. Over this support, formed and screwed as described, is positioned the crown itself, which may be screwed or cemented.
Presently, these connection elements are manufactured by specialized companies which adopt different manufacturing methods. They are supplied to the dentists in a standardized format, which has the inconvenience of not always adapt itself to the individual characteristics of each patient, specifically to the contour of the gum around the implant part, as this does not obey to an uniform format, demanding from the dentist, during the laboratory phase, the addition or subtraction of material to/from these connection elements. Besides the inherently high costs of the connection elements themselves, to the dentist labor are added all the other finishing operations of the connection element, implying in considerable costs in terms of working time.
Attempts to eliminate these problems, or to at least reduce the difficulties existing for the manufacturing of dental prosthetic components, have been effected by the manufacturing and supplying companies of connection elements, to reduce the angular problems which occur during the implant procedure, as the implant must surface from the tooth perimeter. Therefore, presently there already exist in the market connection elements having different configurations in the base portion and/or different angles at the cylindrical body. Even in these cases, however, a perfect adaptation to the specific anatomic details is not possible, in terms of the soft tissues anatomy of the patient and of the positioning of the implant in relation to the crown perimeter, remaining, however the above mentioned difficulties and disadvantages.
Therefore it is an object of the present invention to provide a supporting device for the manufacture of dental prosthetic components, of the above mentioned type, which shall eliminate the prior art difficulties and disadvantages described above, providing a faster, cheaper, and dependable method to manufacture connection elements.
Another object of the present invention is to help the dentist in his work, eliminating addition or subtraction operations to/from the connection elements, so as they can be manufactured in a fast and personalized form, at the dentist office, thereby avoiding the sculpturing phase.